Fix: false positive “Match expression does not handle remaining value: int<...>” for match (count(...)) { ...}

Co-authored-by: ondrejmirtes <104888+ondrejmirtes@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

src/Analyser/TypeSpecifier.php

@@ -2568,7 +2568,7 @@ private function resolveNormalizedIdentical(Expr\BinaryOp\Identical $expr, Scope
 			$argType = $scope->getType($unwrappedLeftExpr->getArgs()[0]->value);
 			$isZero = (new ConstantIntegerType(0))->isSuperTypeOf($rightType);
 			if ($isZero->yes()) {
-				$funcTypes = $this->create($unwrappedLeftExpr, $rightType, $context, $scope)->setRootExpr($expr);
+				$funcTypes = $this->create($leftExpr, $rightType, $context, $scope)->setRootExpr($expr);
 
 				if ($context->truthy() && !$argType->isArray()->yes()) {
 					$newArgType = new UnionType([
@@ -2586,11 +2586,15 @@ private function resolveNormalizedIdentical(Expr\BinaryOp\Identical $expr, Scope
 
 			$specifiedTypes = $this->specifyTypesForCountFuncCall($unwrappedLeftExpr, $argType, $rightType, $context, $scope, $expr);
 			if ($specifiedTypes !== null) {
+				if ($leftExpr !== $unwrappedLeftExpr) {
+					$funcTypes = $this->create($leftExpr, $rightType, $context, $scope)->setRootExpr($expr);
+					return $specifiedTypes->unionWith($funcTypes);
+				}
 				return $specifiedTypes;
 			}
 
 			if ($context->truthy() && $argType->isArray()->yes()) {
-				$funcTypes = $this->create($unwrappedLeftExpr, $rightType, $context, $scope)->setRootExpr($expr);
+				$funcTypes = $this->create($leftExpr, $rightType, $context, $scope)->setRootExpr($expr);
 				if (IntegerRangeType::fromInterval(1, null)->isSuperTypeOf($rightType)->yes()) {
 					return $funcTypes->unionWith(
 						$this->create($unwrappedLeftExpr->getArgs()[0]->value, new NonEmptyArrayType(), $context, $scope)->setRootExpr($expr),
@@ -2616,7 +2620,7 @@ private function resolveNormalizedIdentical(Expr\BinaryOp\Identical $expr, Scope
 
 			$isZero = (new ConstantIntegerType(0))->isSuperTypeOf($rightType);
 			if ($isZero->yes()) {
-				$funcTypes = $this->create($unwrappedLeftExpr, $rightType, $context, $scope)->setRootExpr($expr);
+				$funcTypes = $this->create($leftExpr, $rightType, $context, $scope)->setRootExpr($expr);
 				return $funcTypes->unionWith(
 					$this->create($unwrappedLeftExpr->getArgs()[0]->value, new ConstantStringType(''), $context, $scope)->setRootExpr($expr),
 				);
@@ -2625,7 +2629,7 @@ private function resolveNormalizedIdentical(Expr\BinaryOp\Identical $expr, Scope
 			if ($context->truthy() && IntegerRangeType::fromInterval(1, null)->isSuperTypeOf($rightType)->yes()) {
 				$argType = $scope->getType($unwrappedLeftExpr->getArgs()[0]->value);
 				if ($argType->isString()->yes()) {
-					$funcTypes = $this->create($unwrappedLeftExpr, $rightType, $context, $scope)->setRootExpr($expr);
+					$funcTypes = $this->create($leftExpr, $rightType, $context, $scope)->setRootExpr($expr);
 
 					$accessory = new AccessoryNonEmptyStringType();
 					if (IntegerRangeType::fromInterval(2, null)->isSuperTypeOf($rightType)->yes()) {

tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php

@@ -453,6 +453,12 @@ public function testBug13029(): void
 		$this->analyse([__DIR__ . '/data/bug-13029.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug12790(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-12790.php'], []);
+	}
+
 	#[RequiresPhp('>= 8.0')]
 	public function testBug11310(): void
 	{

tests/PHPStan/Rules/Comparison/data/bug-12790.php

@@ -0,0 +1,24 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug12790;
+
+$r = [];
+$r[] = 'a';
+if (rand(0, 1)) {
+	$r[] = 'b';
+}
+
+echo match (count($r)) {
+	1 => 'one',
+	2 => 'two',
+};
+
+/** @param 'a'|'ab' $s */
+function matchStrlen(string $s): string {
+	return match (strlen($s)) {
+		1 => 'one',
+		2 => 'two',
+	};
+}